Sia Flashes Her Face and Her Nipple in Candid, Boob-Baring Pic

We all know the singer for her signature, elaborate wigs that are always covering her face. But in a rare photo yesterday, she took it off...along with some of her clothes.

Makeup artist and hairstylist Tonya Brewer caught the hilarious moment after Sia finished directing her very first film. In the pic, the singer rocks a bright green face mask, pink furry slippers and a white, silk robe, which happened to slip just far enough over that she accidentally flashed a boob!

"I was a singer for 10 or 11 years to mediocre success," she said at the time. "I was an alcoholic and a drug addict. I sobered up, and I decided I didn't want to be an artist anymore, because I was starting to get a little bit famous and it was destabilizing in some way."

She continued, "I thought, 'What doesn't exist in pop music at the moment?' And it was mystery. I was like, 'There's pictures on Instagram of everyone at the dentist.'"